Method of forming semiconductor device

ABSTRACT

A method includes: abutting a first logic cell having a first cell height to a first memory cell having the first cell height; forming a first conductive rail and a second conductive rail at opposite sides of the first memory cell, respectively; forming a plurality of first conductive rails between the first conductive rail and the second conductive rail; forming a third conductive rail and a fourth conductive rail at opposite sides of the first logic cell, respectively; and forming a plurality of second conductive rails between the third conductive rail and the fourth conductive rail. An amount of the plurality of second conductive rails is larger than an amount of the plurality of first conductive rails.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of U.S. application Ser.No. 17/035,438, filed on Sep. 28, 2020, which is herein incorporated byreference.

BACKGROUND

Static random access memory (SRAM), including bit cells and peripheralcells, are frequently implemented by a semiconductor device. One way torepresent the semiconductor device is with a plan view diagram referredto as a layout diagram with grids. The layout diagram is generated in acontext of design rules. For example, for the peripheral cells in thelayout diagram, an arrangement of each of fin-shaped active regions isrestricted to a corresponding cell height, and it also constrains adensity of active regions and an area scaling of the layout diagram.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a simplified block diagram of a semiconductor device, inaccordance with some embodiments of the present disclosure.

FIG. 2 is a schematic diagram of a memory device corresponding to thesemiconductor device shown in FIG. 1 , in accordance with someembodiments of the present disclosure.

FIG. 3 is a schematic diagram of a memory device corresponding to thesemiconductor device shown in FIG. 1 , in accordance with someembodiments of the present disclosure.

FIG. 4 is a layout diagram of the memory device shown in FIG. 3 , inaccordance with some embodiments of the present disclosure.

FIG. 5 is a layout diagram of a memory device corresponding to thesemiconductor device shown in FIG. 1 , in accordance with someembodiments of the present disclosure.

FIGS. 6A-6B are layout diagrams of the memory device shown in FIG. 3 ,in accordance with some embodiments of the present disclosure.

FIGS. 7A-7B are layout diagrams of the memory device shown in FIG. 3 ,in accordance with some embodiments of the present disclosure.

FIG. 8A is a flow chart of a method for generating an integrated circuit(IC) layout diagram including a memory device, in accordance with someembodiments of the present disclosure.

FIG. 8B is a flow chart of a method for generating an integrated circuit(IC) of a memory device, in accordance with some embodiments of thepresent disclosure.

FIG. 9 is a block diagram of a system for designing an IC layout design,in accordance with some embodiments of the present disclosure.

FIG. 10 is a block diagram of an integrated circuit (IC) manufacturingsystem, and an IC manufacturing flow associated therewith, in accordancewith some embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

The terms used in this specification generally have their ordinarymeanings in the art and in the specific context where each term is used.The use of examples in this specification, including examples of anyterms discussed herein, is illustrative, and in no way limits the scopeand meaning of the disclosure or of any exemplified term. Likewise, thepresent disclosure is not limited to various embodiments given in thisspecification.

Although the terms “first,” “second,” etc., may be used herein todescribe various elements, these elements should not be limited by theseterms. These terms are used to distinguish one element from another. Forexample, a first element could be termed a second element, and,similarly, a second element could be termed a first element, withoutdeparting from the scope of the embodiments. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Furthermore, spatially relative terms, such as “underlying,” “below,”“lower,” “overlying,” “upper” and the like, may be used throughout thedescription for ease of understanding to describe one element orfeature's relationship to another element(s) or feature(s) asillustrated in the figures. The spatially relative terms are intended toencompass different orientations of the device in use or operation inaddition to the orientation depicted in the figures. The structure maybe otherwise oriented (e.g., rotated 90 degrees or at otherorientations) and the spatially relative descriptors used herein maylikewise be interpreted accordingly.

As used herein, “around”, “about”, “approximately” or “substantially”shall generally refer to any approximate value of a given value orrange, in which it is varied depending on various arts in which itpertains, and the scope of which should be accorded with the broadestinterpretation understood by the person skilled in the art to which itpertains, so as to encompass all such modifications and similarstructures. In some embodiments, it shall generally mean within 20percent, preferably within 10 percent, and more preferably within 5percent of a given value or range. Numerical quantities given herein areapproximate, meaning that the term “around”, “about”, “approximately” or“substantially” can be inferred if not expressly stated, or meaningother approximate values.

Reference now made to FIG. 1 . FIG. 1 is a simplified block diagram of asemiconductor device 100, in accordance with some embodiments of thepresent disclosure. The semiconductor device 100 includes a circuitmacro (hereinafter, macro) 102. In some embodiments, the macro 102 is astatic random access memory (SRAM) macro. In some other embodiments, themacro 102 is a macro other than the SRAM macro.

In some embodiments, the macro 102 includes memory cells (not shown inFIG. 1 ) and peripheral circuits (not shown in FIG. 1 ). The memorycells are also referred to as bit cells, and are configured to storememory bits. The peripheral cells are also referred to as logic cellsthat are disposed around the bit cells, and are configured to implementvarious logic functions. The logic functions of the logic cells include,for example, write and/or read decoding, word line selecting, bit lineselecting, data driving and memory self-testing. The logic functions ofthe logic cells described above are given for the explanation purpose.Various logic functions of the logic cells are within the contemplatedscope of the present disclosure.

In some embodiments, the bit cells and the logic cells are used in amemory device including, for example, SRAM. Alternatively stated, thememory device includes at least one bit cell and at least one logiccell, based on the macro 102. In some embodiments, at least one of thebit cells and the logic cells are implemented by 6 or 8 transistors.

Reference now made to FIG. 2 . FIG. 2 is a schematic diagram of a memorydevice MC0 corresponding to the semiconductor device 100 shown in FIG. 1, in accordance with some embodiments of the present disclosure. In someembodiments, the memory device MC0 is generated according to the macro102 shown in FIG. 1 .

For illustration in FIG. 2 , the memory device MC0 includes a bit cell210 and a logic cell 220. The logic cell 220 abuts to the bit cell 210.The logic cell 220 includes active regions AA1, AA2 and AA3 (which arealso referred to as active areas) configured to form transistors. Forsimplicity, each of the active regions AA1, AA2 and AA3 is referenced asAA hereinafter for illustration, because each of the active regions AA1,AA2 and AA3 operates in a similar way in some embodiments. The bit cell210 also includes active regions AA (not shown) for forming transistorsthat are separated from the transistors formed in the logic cell 220.For simplicity of illustration, only few active regions AA areillustrated in the logic cell 220. Various elements for forming thetransistors or other circuit units including, for example, conductivesegments corresponding to sources and drains of the transistors, are notillustrated in FIG. 2 or other embodiments of the present disclosure.

The active regions AA in the logic cell 220 are arranged in columns andinclude active elements 221, 222, 223, 224, 225 and 226. For simplicity,each of the active elements 221, 222, 223, 224, 225 and 226 isreferenced as FN hereinafter for illustration, because each of theactive elements 221, 222, 223, 224, 225 and 226 operates in a similarway in some embodiments. The active elements FN are formed in acorresponding active regions AA. Specifically, the active elements 221and 222 are formed in the active region AA1; the active elements 223 and224 are formed in the active region AA2; and the active elements 225 and226 are formed in the active region AA3. Moreover, the active elementsFN are separated into several groups, including, for example, a firstgroup T1 for forming a transistor, a second group T2 for forming anothertransistor, and a third group T3 for forming the other one transistor.Alternatively stated, one logic cell 220 includes more than threetransistors, and each of these transistors is formed with at least twoactive elements FN. In other way to explain, with reference to FIG. 2 ,three transistors are included in the logic cell 220, and each of thesetransistors is generated based on two active elements FN that areseparated into three groups T1, T2 and T3.

In some embodiments, the active regions AA are polysilicon. In someembodiments, the active regions AA are made of p-type doped material. Insome other embodiments, the active regions AA are made of n-type dopedmaterial. In various embodiments, the active regions AA are configuredto form channels of transistors. In some other embodiments, the activeregions AA are fin-shaped active regions and are configured to form finstructures for forming fin field-effect transistors (FinFET). The activeelements FN formed in these active regions AA are fin structures(hereinafter, fins FN in some embodiments of the present disclosure).For simplicity of illustration, only active regions AA and fins FN areillustrated in the logic cell 220. Various numbers of active regions AAand fins FN in the logic cell 220 are within the contemplated scope ofthe present disclosure.

The configuration of the memory device MC0 is given for illustrativepurpose. Various configurations of the memory device MC0 are within thecontemplated scope of the present disclosure. Moreover, the number andarrangement of the fins FN are given for illustrative purpose. Variousnumbers and arrangements of the fins FN to implement the logic cell 220are within the contemplated scope of the present disclosure. Forexample, in some embodiments, a number of the fins FN in a correspondinggroup is more than two (e.g., three fins FN in the group T1), and thecorresponding transistor is a FinFET with multi-fin structures (e.g.,three-fins FinFET formed in the group T1). In alternative embodiments,the the fins FN are arranged in rows.

Reference now made to FIG. 3 . FIG. 3 is a schematic diagram of a memorydevice MC1 corresponding to the semiconductor device 100 shown in FIG. 1, in accordance with some embodiments of the present disclosure. In someembodiments, the memory device MC1 is generated according to the macro102 shown in FIG. 1 . In some embodiments, the memory device MC1 isconstructed based on the memory device MC0 shown in FIG. 2 .

For illustration in FIG. 3 , the memory device MC1 includes bit cells310, 330 and logic cells 320, 340. The bit cells 310, 330 and the logiccells 320, 340 are arranged in rows and columns as an array. The bitcell 310 is disposed next to the logic cell 320 along one row, and thebit cell 330 is disposed next to the logic cell 340 along another rowthat abuts to the row that is arranged with both of the bit cell 310 andthe logic cell 320.

In some embodiments, the bit cell 310 is identical to the bit cell 330.In some other embodiments, the bit cell 310 is different from the bitcell 330, and the difference between the same including, for example,cell height and number of transistor formation. In various embodiments,the bit cells 310, 330 are identical to the bit cell 210 shown in FIG. 2.

In some embodiments, the bit cell 310 is coupled to at least one bitline that is same as which is coupled to the bit cell 330, configured toreceive bit data transmitted from the bit line. Alternatively stated,the bit cell 310 and the bit cell 330 share at least one bit line forreceiving same bit data. In various embodiments, the bit cell 310 iscoupled to at least one word line that is same as which is coupled tothe bit cell 330, configured to receive program data transmitted fromthe word line. Alternatively stated, the bit cell 310 and the bit cell330 share at least one word line for receiving same program data.

In some embodiments, the logic cell 320 is identical to the logic cell340. In some other embodiments, the logic cell 320 is different from thelogic cell 340, and the difference between the same including, forexample, cell height and logic function. In various embodiments, thelogic cells 320, 340 are identical to the bit cell 210 shown in FIG. 2 .

In some embodiments, the logic cell 320 is coupled to at least onesignal line that is same as which is coupled to the logic cell 340,configured to receive program data transmitted from the signal line. Invarious embodiments, the logic cell 320 is coupled to signal lines thatare alternative from which are coupled to the logic cell 340, configuredto receive program data transmitted from the signal line.

With continued reference to FIG. 3 , the logic cell 320 includes activeregions AA1, AA2 and AA3, and the active regions AA1, AA2 and AA3 areconfigured to form fins 321, 322, 323, 324, 325 and 326 arranged incolumns, respectively. The logic cell 340 includes active regions AA4,AA5 and AA6, and the active regions AA4, AA5 and AA6 are configured toform fins 341, 342, 343, 344, 345 and 346 arranged in columns,respectively. For simplicity, each of the fins 321, 322, 323, 324, 325,326, 341, 342, 343, 344, 345 and 346 is referenced as FN hereinafter forillustration, because each of the fins 321, 322, 323, 324, 325, 326,341, 342, 343, 344, 345 and 346 is fin structure in some embodiments ofthe present disclosure and operates in a similar way in someembodiments.

The fins FN are separated into groups including, with reference to FIG.3 , groups T1, T2, T3, T4, T5 and T6, for forming respectivetransistors. For simplicity, each of the groups T1, T2, T3, T4, T5 andT6 is referenced as TN hereinafter for illustration, because each of thegroups T1, T2, T3, T4, T5 and T6 operates in a similar way in someembodiments. Specifically, in the logic cell 320, the fins 321 and 322included in the active region AA1 are separated into the group T1; thefins 323 and 324 included in the active region AA2 are separated intothe group T2 and the fins 325 and 326 included in the active region AA3are separated into the group T3. In the logic cell 340, the fins 341 and342 included in the active region AA4 are separated into the group T4;the fins 343 and 344 included in the active region AA5 are separatedinto the group T5 and the fins 345 and 346 included in the active regionAA6 are separated into the group T6. Alternatively stated, multipletransistors are formed in the fins FN that are separated into respectivegroups, and these groups are disposed next to each other and arranged incolumns. For example, with reference to FIG. 3 , a transistor (notshown) is formed in the group T1 including the fins 321 and 322, andanother transistor disposed next to that transistor is formed in thegroup T2 including the fins 323 and 324.

Each two adjacent groups TN are separated into one device unit.Specifically, the group T1 and T2 are indicated as a device unit DU1;the group T3 and T4 are indicated as a device unit DU2; and the group T5and T6 are indicated as a device unit DU3. Alternatively stated, onedevice unit DU1, DU2 or DU3 includes two adjacent groups TN, and each ofthese groups TN includes two fins FN for forming one transistor. Withreference to FIG. 3 , the device unit DU1 includes the groups T1 and T2that include the fins 321, 322, 323 and 324 for forming two adjacenttransistors; the device unit DU2 includes the groups T3 and T4 thatinclude the fins 325, 326, 341 and 342 for forming another two adjacenttransistors; and the device unit DU3 includes the groups T5 and T6 thatinclude the fins 343, 344, 345 and 346 for forming the other twoadjacent transistors. In another way to explain, the device unit DU1 andhalf of the device unit DU2 are arranged in the logic cell 320, and halfof the device unit DU2 and the device unit DU3 are arranged in the logiccell 340. Therefore, more than one device unit DU1, DU2 or DU3 isarranged in the logic cell 320 or 340, and more than two device unitsDU1, DU2 or DU3 are arranged in the logic cells 320 and 340 in thememory device MC1. For simplicity, each of the device units DU1, DU2 andDU3 is referenced as DU hereinafter for illustration, because each ofthe device units DU1, DU2 and DU3 operates in a similar way in someembodiments.

In some embodiments, the transistors formed in at least two adjacentgroups TN are different from one another. For example, with reference toFIG. 3 , in the logic cell 320, a transistor formed in the group T1 is ap-type metal oxide semiconductor (PMOS) transistor, and a transistorformed in the group T2 is a n-type metal oxide semiconductor (NMOS)transistor. Furthermore, the device unit DU1, including the group T1 andT2, includes one PMOS transistor and one NMOS transistor. In some otherembodiments, the transistors formed in at least two adjacent groups TNare identical to each other. For example, with reference to FIG. 3 , inthe logic cell 320, a transistor formed in the group T2 is a NMOStransistor, and a transistor formed in the group T3 is also a NMOStransistor. In various embodiments, types of the transistors formed inthe corresponding groups TN are determined based on the arrangement ofthe device units DU, and each of the device units DU includes twotransistors of different types. For example, with reference to FIG. 3 ,the device unit DU1 includes a PMOS transistor formed in the group T1and a NMOS transistor formed in the group T2; the device unit DU2includes a NMOS transistor formed in the group T3 and a PMOS transistorformed in the group T4; and the device unit DU3 includes a PMOStransistor formed in the group T5 and a NMOS transistor formed in thegroup T6. In some embodiments, one device unit DU including at least onePMOS and at least one NMOS is also indicated as one logic circuit unit,for implementing a fundamental logic function.

The above configuration of the memory device MC1 is provided forillustrative purposes. Various implementations of the memory device MC1are within the contemplated scope of the present disclosure. Forexample, in various embodiments, the bit cells 310 and 330 are arrangedin rows, and the logic cells 320 and 340 are arranged in columns.

In some approaches, only few fins formed in a corresponding activeregion are arranged in the logic cells. Specifically, in one logic cell,a number of the fins is limited to being below four, for formingtransistors that are less than two (i.e., less than one device unit).Alternatively stated, in two adjacent logic cells, less than two deviceunits are included, and it has low active region density and furtherleads to poor area scaling in one memory device.

Compared to the above approaches, in the embodiments of the presentdisclosures, for example with reference to FIG. 3 , in one logic cell320 or 340, a number of the fins FN is at least six, for formingtransistors that are more than three and forming device units DU thatare more than one and half. Alternatively stated, with reference 3, itis able to arrange three device units DU for implementing three logiccircuit units in two adjacent logic cells 320 and 340. Accordingly, intwo adjacent logic cells 320 and 340 of the memory device, both of theactive region density and area scaling increase, and it further achievesone and half times of the device unit density.

Reference now made to FIG. 4 . FIG. 4 is a layout diagram ML1 of thememory device MC1 shown in FIG. 3 , in accordance with some embodimentsof the present disclosure. For simplicity of illustration, only fins FNare illustrated in the layout diagram ML1, and each of the fins FN isdisposed in a corresponding active region (not labeled). Variouspatterns for forming transistors or other circuit units including, forexample, conductive segments and vias, are not illustrated in FIG. 4 orother embodiments of the present disclosure. With respect to theembodiments of FIG. 3 , like elements in FIG. 4 are designated with thesame reference numbers for ease of understanding.

With references to FIGS. 3 and 4 , the bit cell 410 corresponds to thebit cell 310 shown in FIG. 3 ; the bit cell 430 corresponds to the bitcell 330 shown in FIG. 3 ; the logic cell 420 corresponds to the logiccell 320 shown in FIG. 3 ; and the logic cell 440 corresponds to thelogic cell 340 shown in FIG. 3 . Furthermore, in the logic cell 420, thefins 421, 422, 423, 424, 425 and 426 correspond to the fins 321, 322,323, 324, 325 and 326 shown in FIG. 3 , respectively; and in the logiccell 440, the fins 441, 442, 443, 444, 445 and 446 correspond to thefins 341, 342, 343, 344, 345 and 346 shown in FIG. 3 , respectively.

Compared to the embodiments illustrated in FIG. 3 , the bit cells 410and 430 include separated fins FN. For simplicity, only few fins FN inbit cells 410 and 430 are labeled in FIG. 4 for illustration, including,for example, the fins 411, 412, 413, 414, 415 and 416 in the bit cell410, and the fins 431, 432, 433, 434, 435 and 436 in the bit cell 430.In some embodiments, each of the fins FN in the bit cells 410 and 430 isconfigured to form one transistor. For example, in the bit cell 410, afirst transistor is formed in an active region (not shown) including thefin 411; a second transistor that is disposed next to the firsttransistor is formed in an active region including the fin 412; a thirdtransistor is formed in an active region including the fin 413; a fourthtransistor is formed in an active region including the fin 414; a fifthtransistor is formed in an active region including the fin 415; and asixth transistor is formed in an active region including the fin 416.Therefore, there are at least six transistors generated in one bit cell410. Similarly, the bit cell 430 also includes six transistors formedwith the corresponding fins FN.

Furthermore, the bit cell 410 has a cell height H1, and the bit cell 430has a cell height H2. In some embodiments, the cell height H1 is equalto the cell height H2. In some other embodiments, the cell height H1 issubstantially equal to the cell height H2. In various embodiments, thecell height H1 is different from the cell height H2. In someembodiments, the cell height H1 or H2 is determined based on a type ofthe bit cell 410 or 430 that is one of standard cells in a library ofstandard cells (which is discussed with reference to FIG. 9 ). Invarious embodiments, the bit cells 410 and 430 are symmetricalstructures with respect to columns.

In some embodiments, a cell height of the logic cell 420 is determinedbased on the cell height H1 of the bit cell 410, and a cell height ofthe logic cell 440 is determined based on the cell height H2 of the bitcell 430. In various embodiments, the logic cell 420 disposed next tothe bit cell 410 also has the cell height H1, and the logic cell 440disposed next to the bit cell 430 also has the cell height H2.

A width of the fins FN is a fixed width. In some embodiments of thepresent disclosure, the active regions (e.g., active regions AA1-AA6shown in FIG. 3 ) including the fins FN are fin-shaped active regionsfor forming fin structures of the transistors, and the fins FN are finstructures. The fixed width of each of the fins FN is indicated as onefin width, for example, a fin width P of the fin 421 shown in FIG. 4 .With continued reference to FIG. 4 , each of the fins FN in all of thebit cells 410, 430 and logic cells 420 and 440 has a fixed width, and isalso referred to as the fin width P. For simplicity, only one fin widthP is illustrated with the fin 431.

At least one length of the fins FN in the bit cells 410 and 430 isdifferent from another length of the same. A length of the fins FN inthe logic cells 420 and 440 is same as one another. In some embodiments,a length of the fins FN in the bit cells 410 and 430 is different from alength of the fins FN in the logic cells 420 and 440. In some otherembodiments, a length of the fins FN in the bit cells 410 and 430 isshorter than a length of the fins FN in the logic cells 420 and 440. Invarious embodiments, a length of the fins FN in the bit cells 410 and430 is substantially equal to a length of the fins FN in the logic cells420 and 440.

Moreover, a distance between each two adjacent groups TN is indicated asa distance S1 shown in FIG. 4 . In some embodiments, the distance S1between two adjacent active regions (i.e., two adjacent groups TN) isalso indicated as an active region spacing that is restricted to designrules of the layout diagram ML1. Alternatively stated, one fin FN of onegroup TN (referred to as group T1′ herein) is separated from another onefin FN of another group TN (referred to as group T2′ herein). The groupT1′ is disposed next to the group T2′ and separated from each other byat least one active region spacing. With continued reference to FIG. 4 ,the distance between each two adjacent groups TN, including, forexample, between the groups T1 and T2, between the groups T2 and T3,between the groups T3 and T4, between the groups T4 and T5, and betweenthe groups T5 and T6, is same as one another, and is equal to thedistance S1. For simplicity, only one distance S1 is illustrated betweenthe group T1 and the group T2 in FIG. 4 . Specifically, the distance S1is a distance between a top edge of one fin FN in one group T1′ and atop edge of one fin in another group T2′ that is adjacent to the groupT1′. For example, as illustrated in FIG. 4 , the distance S1 is adistance between a top edge of the fin 422 in the group T1 and a topedge of the fin 423 in the group T2.

In some embodiments, a distance between at least two adjacent groups TNis different from a distance between other two adjacent groups TN.Alternatively stated, at least two adjacent groups TN are separated by afirst distance, and at least other two adjacent groups TN are separatedby a second distance. The first distance is different from the seconddistance. For example, with reference to FIG. 4 , the group T1 isseparated from the group T2 by a first distance (which is the distanceS1); the group T2 is separated from the group T3 by a second distance(not shown in FIG. 4 ); the group T3 is separated from the group T4 by athird distance (not shown in FIG. 4 );the group T4 is separated from thegroup T5 by a fourth distance (not shown in FIG. 4 ); and the group T5is separated from the group T6 by a fifth distance (not shown in FIG. 4). The first distance is different from at least one of the seconddistance, the third distance, the fourth distance, or the fifthdistance. In another way to explain, at least one active region spacingamong several groups TN is different from the others.

Furthermore, a distance between each two adjacent fins FN of one groupTN is indicated as a distance S2 shown in FIG. 4 . In some embodiments,the distance S2 between two adjacent fins FN of each groups TN is alsoindicated as a fin pitch (which will discuss with reference to FIGS.6A-6B) that is restricted to at least one of the cell height, the designrules of the layout diagram ML1 and limitations of the fabrication.Alternatively stated, one fin FN (referred to as fin F1 herein) isseparated from another one fin FN (referred to as fin F2 herein). Thefins F1 and F2 are indicated as one group for forming a same transistor.The fin F1 is disposed next to the fin F2, and is separated from the finF2 by at least one fin pitch. With continued reference to FIG. 4 , thedistance between each two adjacent fins FN of a corresponding group TN,including, for example, between the fins 421 and 422 of the group T1,between the fins 423 and 424 of the group T2, between the fins 425 and426 of the group T3, between the fins 441 and 442 of the group T4,between the fins 442 and 444 of the group T5, and between the fins 445and 446 of the group T6, is same as one another, and is equal to thedistance S2. For simplicity, only one distance S2 is illustrated betweenthe adjacent fins 423 and 424 of the group T2 in FIG. 4 .

In some embodiments, a distance between two adjacent fins FN of onegroup TN is different from a distance two adjacent fins FN of anothergroup TN. Alternatively stated, two adjacent fins FN of at least onegroup TN are separated from each other by a first distance, and twoadjacent fins FN of at least another group TN are separated from eachother by a second distance. The first distance is different from thesecond distance. For example, with reference to FIG. 4 , the fins 421and 422 of the group T1 are separated by a first distance (not shown inFIG. 4 ); the fins 423 and 424 of the group T2 are separated by a seconddistance (which is the distance S2); the fins 425 and 426 of the groupT3 are separated by a third distance; the fins 441 and 442 of the groupT4 are separated by a fourth distance; the fins 442 and 444 of the groupT5 are separated by a fifth distance; and the fins 445 and 446 of thegroup T6 are separated by a sixth distance. The first distance isdifferent from at least one of the second distance, the third distance,the fourth distance, the fifth distance, or the sixth distance.

The configuration of layout diagram ML1 is given for illustrativepurposes. Various configurations of layout diagram ML1 are within thecontemplated scope of the present disclosure. For example, in variousembodiments, each fins FN in the bit cells 410 and 430 has a length thatis substantially equal to each other.

Reference now made to FIG. 5 . FIG. 5 is a layout diagram ML2 of amemory device corresponding to the semiconductor device 100 shown inFIG. 1 , in accordance with some embodiments of the present disclosure.In some embodiments, the layout diagram ML2 shown in FIG. 5 is analternative embodiment of the layout diagram ML1 shown in FIG. 4 . Withrespect to the embodiments of FIG. 4 , like elements in FIG. 5 aredesignated with the same reference numbers for ease of understanding.

Compared to the embodiments illustrated in FIG. 4 , a number of the finsFN included in each of the bit cells 510 and 530 is more that of thesame included in each of the bit cells 410 and 430 shown in FIG. 4 .Alternatively stated, a number of transistors formed in the bit cells510 and 530 is more than that of the same formed in the bit cells 410and 430 shown in FIG. 4 . For example, with reference to FIG. 5 , in thebit cell 510, transistors corresponding to groups T9, T10, T11, T12,T13, T14, T15 and T16 are formed in the corresponding active regions(not labeled) that include fins FN (which is not labeled one-by-one forsimplified illustration). Therefore, there are at least eighttransistors generated in one bit cell 510, which is more than at leastsix transistors generated in the bit cell 410 in FIG. 4 . Similarly, thebit cell 530 also includes eight transistors, including, for example,transistors corresponding to groups T17, T18, T19, T20, T21, T22, T23and T24, formed in corresponding active regions (not labeled) thatinclude the fins FN.

Moreover, a number of the fins FN included in each of the logic cells520 and 540 is more that of the same included in each of the logic cells420 and 440 shown in FIG. 4 , respectively. Alternatively stated, anumber of transistors formed in the logic cells 520 and 540 is more thatof the same formed in the logic cells 420 and 440 shown in FIG. 4 . Forexample, with reference to FIG. 5 , in the logic cells 520, thetransistors corresponding to groups T1, T2, T3 and T4 are formed.Therefore, there are at least four transistors generated in one logiccell 520, which is more than three transistors generated in the logiccell 420 in FIG. 4 . Similarly, the logic cells 540 also include fourtransistors corresponding to groups T5, T6, T7 and T8.

Furthermore, in some embodiments, two adjacent groups TN are separatedinto one device unit DU. A number of the device units DU included ineach of the logic cells 520 and 540 is more that of the same included ineach of the logic cells 420 and 440 shown in FIG. 4 , respectively. Forexample, with reference to FIG. 5 , at least two device units DU,including, for example, device units DU1 including the groups T1 and T2,and device units DU2 including the groups T3 and T4, are included in thelogic cells 520. It is more than 0.5 device unit DU included in thelogic cell 420 shown in FIG. 4 . Similarly, the logic cells 540 alsoinclude two device units DU, including, for example, device unit DU3including the groups T5 and T6, and device unit DU4 including the groupsT7 and T8.

Reference now made to FIGS. 6A and 6B. Each of FIGS. 6A-6B is a layoutdiagram ML1 of the memory device MC1 shown in FIG. 3 , in accordancewith some embodiments of the present disclosure. In some embodiments,the layout diagram ML1 shown in FIGS. 6A-6B is alternative embodimentsof the layout diagram ML1 shown in FIG. 4 . With respect to theembodiments of FIGS. 3-4 , like elements in FIGS. 6A-6B are designatedwith the same reference numbers for ease of understanding. Forsimplicity, with respect to the embodiments of FIGS. 3-4 , some ofelements in FIGS. 6A-6B are not labeled with identical elements for easeof understanding.

Compared to the embodiments illustrated in FIG. 4 , active region gridsFN′ are illustrated, and extend across the bit cells and logic cellsalong rows. In some embodiments of the present disclosure, the fins FNare fin structures of the transistors, and the active region grids FN′are indicated as fin grids FN′ hereinafter. In some embodiments, a widthof the fin grids FN′ is equal to each other, and is further equal to awidth of each fins FN. Alternatively stated, each of the fin grids FN′has a width that is equal to a fixed width of the fins FN, which isreferred to as the fin width P shown in FIGS. 4 and 6A. In someembodiments, a distance between each two adjacent fin grids FN′ is equalto each other, and is referred to as the fin pitch. In variousembodiments, the fin grids FN′ are reference grids for generating thelayout diagram ML1. Alternatively stated, the layout diagram ML1including the bit cells and the logic cells is generated based on thefin grids FN′.

Distances between each two adjacent fins FN along columns areillustrated in FIG. 6A, and distances between each two adjacent fins FNalong rows are illustrated in FIG. 6B. Alternatively stated, verticaldistances between the fins FN are illustrated in FIG. 6A, and horizontaldistances between the fins FN are illustrated in FIG. 6B. In someembodiments, the distances illustrated in FIGS. 6A-6B are also referredto as intervals between the fins FN. For example, with reference to FIG.6A, a vertical distance between fins FN (i.e., indicated as distance S3)is calculated from a bottom edge of one fin FN (i.e., indicated as groupT7) to a top edge of the other fin FN (i.e., indicated as group T8). Asanother example illustrated in FIG. 6B, a horizontal distance betweenfins FN (i.e., indicated as distance D3) is calculated from a right edgeof one fin FN (i.e., indicated as group T7 shown in FIG. 6A) to a leftedge of the other fin FN (i.e., indicated as group T1). The distancesshown in FIGS. 6A-6B are given for illustrative purpose. Variousconfigurations of distances are within the contemplated scope of thepresent disclosure.

With reference to FIG. 6A, the fins FN in the bit cells are separated bydifference distances along columns. For the leftmost-column fins FN inthe bit cells (indicated as a column C1), twelve fins FN are arranged inrows and separated from each other by different distances including, forexample, from the top row to the bottom row, distances S3, S5, S5, S5,S3, S5, S3, S5, S5, S5 and S3. For the middle-column fins FN in the bitcells (indicated as a column C2), twelve fins FN are arranged in rowsand separated from each other by different distances including, forexample, from the top row to the bottom row, distances S3, S6, S3, S6,S3, S5, S3, S6, S3, S6 and S3. For the rightmost-column fins FN in thebit cells (indicated as a column C3), eight fins FN are arranged in rowsand separated from each other by different distances including, forexample, from the top row to the bottom row, distances S3, S7, S3, S5,S3, S7 and S3.

Furthermore, in the bit cells, some of the fins FN are directly disposedin the fin grids FN′ in the layout diagram ML1. Alternatively stated,some of the fins FN in the bit cells are directly overlapped with thefin grids FN′ in a layout view, and it is also indicated that these finsFN are arranged on the fin grids FN′. On the other hand, some of thefins FN in the bit cells are separated from the fin grids FN′ in alayout view, and it is also indicated that these fins FN are arrangedoff the fin grids FN′. In some embodiments, some of the fins FN in thebit cells are partially overlapped with the fin grids FN′ in a layoutview, and it is also indicated as these fins FN being arranged off thefin grids FN′. For example, with reference to FIG. 6A, a group T9 in themiddle-column C2 of the bit cells, is completely overlapped with thecorresponding fin grid FN′, and a group T8 in the rightmost-column C3 inthe bit cells, is not overlapped with the corresponding fin grid FN′.

The fins FN in the logic cells are separated by different distancesalong columns. Specifically, in the logic cells, two adjacent fins FN inthe corresponding groups TN are separated from one another by a firstspacing (indicated as a distance S3). Furthermore, two adjacent groupsTN are separated from one another by a second spacing (indicated as adistance S4).

In some embodiments, each of the fins FN in a corresponding group TN isseparated by a same spacing (e.g., the distance S3 shown in FIG. 6A). Insome other embodiments, a distance between two adjacent fins FN in onegroup TN is different from a distance between two adjacent fins FN inanother group TN. For example, with continued reference to FIG. 6A, twoadjacent fins FN in the group T1 are separated from each other by thedistance S3, and two adjacent fins FN in the group T2 are separated fromeach other by a distance that is different from the distance S3.

In some embodiments, each two adjacent of the groups TN is separatedfrom each other by a same spacing (e.g., the distance S4 shown in FIG.6A). For example, with continued reference to FIG. 6A, two adjacentgroups T1 and T2 are separated from each other by the distance S4. Insome other embodiments, at least two adjacent groups TN are separatedfrom the others by different spacing. Alternatively stated, at least twoadjacent groups TN are separated from one another by a first distance,and another two adjacent groups TN are separated from one another by asecond distance that is different from the first distance. For example,with continued reference to FIG. 6A, the distance between the groups T1and T2 is different from at least one distance between the groups T2 andT3, between the groups T3 and T4, between the groups T4 and T5, orbetween the groups T5 and T6.

Furthermore, in the logic cells, some of the fins FN are partiallydisposed in the fin grids FN′ in the layout diagram ML1. Alternativelystated, some of the fins FN in the logic cells are partially overlappedwith the fin grids FN′ in a layout view, and it is also indicated thatthese fins FN are arranged off the fin grids FN′. In some embodiments,some of the fins FN in the logic cells are separated from the fin gridsFN′ in a layout view, and it is also indicated as these fins FN beingarranged off the fin grids FN′. In various embodiments, in the logiccells, some of the fins FN are directly disposed in the fin grids FN′ inthe layout diagram ML1. Alternatively stated, some of the fins FN in thelogic cells are directly overlapped with the fin grids FN′ in a layoutview, and it is also indicated that these fins FN are arranged on thefin grids FN′. For example, with reference to FIG. 6A, the fins FN arearranged off the fin grids FN′.

In some embodiments, since the layout diagram ML1 is generated based onthe fin grids FN′, the distances between two adjacent fins FN aredetermined based on the fin pitch. Furthermore, design of the fins FNfor forming the fin structures of transistors is also based on theadvanced technology. Alternatively stated, the arrangement of the finsFN is determined based on the fin grids FN′ and the fabricationlimitations. In some embodiments, the arrangement of the fins FN isfurther determined based on the cell height of the bit cells.

For example, with reference to FIG. 6A, for the cells with the cellheight H1 and H2, the distance S3 is substantially equal to a distancebetween two adjacent fin grids FN′ (i.e., one fin pitch) subtracted thewidth of the fin grids FN′ (i.e., the distance

P). Alternatively stated, these two adjacent fin grids FN′ are separatedfrom each other by the distance S2 (which is discussed with reference toFIG. 4 ), and it is also indicated as one fin pitch in some embodiments.The distance S4 is in a range of one fin pitch to two times of the finpitch (i.e., S4=1*fin pitch−2*fin pitch). The distance S5 is in a rangeof one fin pitch to two times of the fin pitch (i.e., S5=1*finpitch−2*fin pitch), and is larger than the distance S3. The distance S6is in a range of two times of the fin pitch to three times of the finpitch (i.e., S6=2*fin pitch−3*fin pitch). The distance S7 is in a rangeof five times of the fin pitch to six times of the fin pitch (i.e.,S7=5*fin pitch−6*fin pitch).

In some embodiments, a distance between at least two adjacent groups TNin the logic cells is not an integral of the fin pitch. For example, insome embodiments, the distance S4 between two adjacent groups TN issubstantially equal to the fin pitch multiplied by a number, which isnot an integral and is in a range of one to two. Specifically, thedistance S4 is a distance between a top edge of one fin FN in the groupT1 and a top edge of one fin FN in the group T2. The distance S4 is notan integral multiple of the fin pitch. On the other hand, the distanceS2 (which is shown in FIG. 4 ) between two adjacent fins FN of acorresponding group TN is substantially equal to the fin pitchmultiplied by an integral, which is one. This integral is smaller thansuch number. For example, the integral is equal to 1, and thus thedistance S2 between two adjacent fins FN is equal to the fin pitchmultiplied by 1. The number is equal to 1.2 which is larger than theintegral 1, and thus the distance S4 between two adjacent groups TN isequal to fin pitch multiplied by 1.2. In some other embodiments, thenumber is smaller than the integral, and the number is not an integraleither. In some other embodiments, a distance between at least twoadjacent groups TN in the logic cells is an integral of the fin pitch,when these two adjacent groups TN are arranged off the fin grids FN′ andhave a same shift with respect to the fin grids FN′.

Moreover, some fins FN in the bit cells are not aligned with some finsFN in the logic cells, with respect to the neighboring fin grids FN′among these fins FN. Alternatively stated, at least one fin FN in thebit cells is not aligned with or is substantially aligned with at leastone fin FN in the logic cells along the rows. For example, in someembodiments, with continued reference to FIG. 6A, two groups T7 and T8in the rightmost-column C3 of the bit cells are arranged off the fingrids FN′, and the group T1, disposed next to these groups T7 and T8along the rows, are arranged off the fin grids FN′ either. Since theseparation between the groups T7 and T8 and the fin grids FN′ isdifferent from that between the group T1 and the fin grids FN′, thegroups T7 and T8 in the bit cell are not aligned with the group T1 inthe logic cell along the rows. The groups T11 and T12 in therightmost-column C3 of the bit cells are not aligned with the group T3in the logic cell along the rows. Similarly, in the rightmost-column C3of the bit cells, the groups T13 and T14 are not aligned with the groupT4 in the logic cell along the rows, and the groups T17 and T18 are notaligned with the group T6 in the logic cell along the rows.

In some embodiments, some fins FN in the bit cells are aligned with somefins FN in the logic cells, with respect to the neighboring fin gridsFN′ among these fins FN. Alternatively stated, at least one fin FN inthe bit cells is aligned with at least one fin FN in the logic cellsalong the rows. For example, with continued reference to FIG. 6A, in themiddle-column C2 of the bit cells, the groups T9 and T10 are alignedwith the group T2 in the logic cell along the rows, and the groups T15and T16 are aligned with the group T5 in the logic cell along the rows.

With reference to FIG. 6B, the fins FN in the logic cells are separatedby different distances along rows. In the bit cells, the fins FN in theleftmost-column C1 is separated from the fins FN in the middle-column C2by distances including, for example, from the top row to the bottom row,distances D1, D2, D1, D1, D1, D2 and D1. In some embodiments, the finsFN in the bit cells are separated by a same distance along rows. Forexample, with continued reference to FIG. 6A, the fins FN in themiddle-column C2 is separated from the fins FN in the rightmost-columnC3 by distances including, for example, from the top row to the bottomrow, distances D1, D1, D1 and D1.

Furthermore, the groups between the bit cells and the logic cells areseparated by different distances along rows. Specifically, one fin FN inthe bit cells is separated from the fins FN of the groups TN by a firstdistance, and another one fin FN in the bit cells is separated from thefins FN of the groups TN by a second distance that is different from thefirst distance. For example, with continued reference to FIG. 6B, thegroup T8 in the rightmost-column C3 of the bit cells (which is labeledin FIG. 6A) is separated from the group T1 of the logic cells by adistance D3; the group T10 in the middle-column C2 (which is labeled inFIG. 6A) is separated from the group T2 by a distance D4; the group T11in the rightmost-column C3 (which is labeled in FIG. 6A) is separatedfrom the group T2 by the distance D3; the group T14 in therightmost-column C3 of the bit cells (which is labeled in FIG. 6A) isseparated from the group T4 by the distance D3; the group T16 in themiddle-column C2 (which is labeled in FIG. 6A) is separated from thegroup T5 by the distance D4; and the group T17 in the rightmost-columnC3 (which is labeled in FIG. 6A) is separated from the group T6 by thedistance D3.

In some embodiments, the arrangement of the fins FN is determined basedon at least the fin grids FN′ or active areas for forming gatestructures of transistors. As such, the distances between the fins FN inthe bit cells and the fins FN in the logic cells along the rows areassociated with at least the fin pitch or a poly pitch which is, in someembodiments, referred to as a minimum distance between two adjacent gatestructures. For example, with reference to FIG. 6B, the distance D1 issubstantially equal to one poly pitch; the distance D2 is substantiallyequal to two times of the poly pitch (i.e., D2≈2*poly pitch); thedistance D3 is substantially in a range of four times of the poly pitchto seven times of the poly pitch (i.e., D3=4*poly pitch−7*poly pitch);and the distance D4 is substantially in a range of seven times of thepoly pitch to ten times of the poly pitch (i.e., D4=7*poly pitch−10*polypitch).

The above configuration of the layout diagram ML1 is provided forillustrative purposes. Various implementations of the layout diagram ML1are within the contemplated scope of the present disclosure.

In some approaches, when the fins are arranged in the logic cells, eachof the fins is arranged on the fin grids. As such, the active regionspacing between two adjacent groups of the fins is limited to being asan integral of the fin pitch, and further affects the active regiondensity of the memory device. Moreover, since the active region spacingis constrained, it does not provide a customized arrangement of the finsformed in the active regions.

Compared to the above approaches, in the embodiments of the presentdisclosures, for example with reference to FIG. 4, 6A or 6B, in thelogic cells, at least one of the fins FN is arranged off the fin gridsFN′. Accordingly, the active region spacing between two adjacent groupsTN of the fins FN is not limited by the fin pitch constraint. Also, itmay provide a dense active region density of the memory device, and alsoprovide a customized arrangement of the fins FN formed in thecorresponding active regions (which are the active regions AA shown inFIG. 3 ).

Reference now made to FIGS. 7A-7B. Each of FIGS. 7A-7B is a layoutdiagram ML1 of the memory device MC1 shown in FIG. 3 , in accordancewith some embodiments of the present disclosure. In some embodiments,the layout diagram ML1 shown in FIGS. 7A-7B are alternative embodimentsof the layout diagram ML1 shown in FIG. 4 or FIGS. 6A-6B. With respectto the embodiments of FIGS. 3, 4, 6A and 6B, like elements in FIGS.7A-7B are designated with the same reference numbers for ease ofunderstanding. For simplicity, with respect to the embodiments of FIGS.3, 4, 6A and 6B, some of elements in FIGS. 7A-7B are not labeled withidentical elements for ease of understanding.

Compared to the embodiments illustrated in FIG. 4 , the layout diagramML1 further includes conductive rails disposed in a metal-zero (M0)layer, and the M0 layer is disposed above the fins FN. The conductiverails include power rails 711, 713, 715, 717 and 719, and signal rails712, 714, 716 and 718 disposed in the bit cells, and also includes powerrails 731, 737, 743 and 749, and signal rails 732, 733, 734, 735, 736,738, 739, 740, 741, 742, 744, 745, 746, 747 and 748 disposed in thelogic cells. For simplicity, each of the power rails 711, 713, 715, 717,719, 731, 737, 743 and 749 is referenced as PG hereinafter forillustration, because each of the power rails 711, 713, 715, 717, 719,731, 737, 743 and 749 operates in a similar way in some embodiments. Forsimplicity, each of the signal rails 732, 733, 734, 735, 736, 738, 739,740, 741, 742, 744, 745, 746, 747 and 748 is referenced as SLhereinafter for illustration, because each of the signal rails 732, 733,734, 735, 736, 738, 739, 740, 741, 742, 744, 745, 746, 747 and 748operates in a similar way in some embodiments.

With references to FIGS. 7A-7B, the power rails PG in the bit cells orin the logic cells are separated to each other along the columns. Thesignal rails SL in the bit cells or in the logic cells are disposedbetween the power rails PG and separated from each other along thecolumns. Both of the power rails PG and the signal rails SL are parallelto each other, and extend along rows.

In some embodiments, the power rails PG and the signal rails SL in thebit cells are separated from each other evenly. Alternatively stated, inthe bit cells, a distance between any two adjacent rails of the powerrails PG and the signal rails SL is same from the others. For example,with reference to FIGS. 7A-7B, a distance between the power rail 711 andthe signal rail 712 is equal to a distance between including, the signalrail 712 and the power rail 713, and the power rail 713 and the signalrail 714, and so on. In some other embodiments, in the bit cells, atleast one distance between the power rails PG and the signal rails SL isdifferent from the others thereof. For example, with reference to FIGS.7A-7B, a distance between the power rail 711 and the signal rail 712, orbetween the signal rail 714 and the power rail 715, or between the powerrail 715 and the signal rail 716, or between the signal rail 718 and thepower rail 719, is equal to a first rail spacing. A distance between thesignal rail 712 and the power rail 713, or between the power rail 713and the signal rail 714, or between the signal rail 716 and the powerrail 717, or between the power rail 717 and the signal rail 718, isequal to a second rail spacing. The first rail spacing is also indicatedas a distance S11 shown in FIG. 7B, and the second rail spacing isindicated as a distance S12 shown in FIG. 7B. The first rail spacing isdifferent from the second rail spacing.

In some embodiments, the power rails PG and the signal rails SL in thelogic cells are separated from each other evenly. Alternatively stated,in the logic cells, a distance between any two adjacent rails of thepower rails PG and the signal rails SL is same from the others. Forexample, with reference to FIGS. 7A-7B, a distance between the powerrail 731 and the signal rail 732 is equal to a distance betweenincluding, the signal rails 732 and 733, the signal rails 733 and 734,the signal rails 734 and 735, the signal rails 735 and 736, and thesignal rail 736 and the power rail 737, and so on. This distance betweentwo adjacent rails of the power rails PG and the signal rails SL is alsoindicated as a distance S13 shown in FIG. 7B. In some other embodiments,in the bit cells, at least one distance between the power rails PG andthe signal rails SL is different from the others of the same. Forexample, with reference to FIGS. 7A-7B, a distance between the powerrail 731 and the signal rail 732 is equal to a third rail spacing, and adistance between the signal rails 732 and 733 is equal to a fourth railspacing. The third rail spacing is different from the fourth railspacing.

For illustration in FIG. 7A, in the bit cells, the power rail 711 isdirectly disposed over a top edge of the bit cells in a layout view. Thepower rail 715 is directly disposed over an intersected edge between twoadjacent bit cells and the power rail 719 is directly disposed over abottom edge of the bit cells, in a layout view. The signal rail 712 isdisposed between the power rails 711 and 713. The signal rail 712 isalso disposed over the fins FN including the fin 412. Furthermore, thesignal rail 714 is disposed between the power rails 713 and 715. Thesignal rail 714 is also disposed over the fins FN including the fin 415.Moreover, the signal rail 716 is disposed between the power rails 715and 717. The signal rail 716 is also disposed over the fins FN includingthe fin 432. The signal rail 718 is disposed between the power rails 717and 719. The signal rail 718 is also disposed over the fins FN includingthe fin 435.

In some embodiments, the power rail 711 is coupled through vias (notshown) to transistors formed in the fins FN including the fin 411. Thesignal rail 712 is coupled through vias to transistors formed in thefins FN including the fins 411 and 412. The power rail 713 is coupledthrough vias to transistors formed in the fins FN including the fins 413and 414. The signal rail 714 is coupled through vias to transistorsformed in the fins FN including the fins 415 and 416. The power rail 715is coupled through vias to transistors formed in the fins FN includingthe fins 416 and 431. The signal rail 716 is coupled through vias totransistors formed in the fins FN including the fins 431 and 432. Thepower rail 717 is coupled through vias to transistors formed in the finsFN including the fins 433 and 434. The signal rail 718 is coupledthrough vias to transistors formed in the fins FN including the fins 435and 436. The power rail 719 is coupled through vias to transistorsformed in the fins FN including the fin 436.

With continued reference to FIG. 7A, in the logic cells, the power rail731 is directly disposed over a top edge of the logic cells, and thepower rail 749 is directly disposed over a bottom edge of the logiccells in a layout view. The signal rail 732 is partially disposed overthe fin 421. Alternatively stated, the signal rail 732 is partiallyoverlapped with the fin 421 in a layout view. Furthermore, the signalrail 733 is directly overlapped with the fin 422 in a layout view. Thesignal rail 734 is not overlapped with the fins FN. Alternativelystated, the signal rail 734 is separated from the fin 422 of one group(i.e., the group T1 shown in FIG. 4 ) and the fin 423 of anotheradjacent group (i.e., the group T2 shown in FIG. 4 ). The signal rail735 is directly overlapped with the fin 423 in a layout view. The signalrail 736 is substantially overlapped with the fin 424 completely in alayout view. Alternatively stated, the signal rail 736 is substantiallydisposed over the fin 424. Moreover, the power rail 737 is notoverlapped with the fins FN. Alternatively stated, the power rail 737 isseparated from the fin 424 of one group (i.e., the group T2 shown inFIG. 4 ) and the fin 425 of another adjacent group (i.e., the group T3shown in FIG. 4 ).

In some embodiments, the power rail 731, the signal rails 732, 733, 734,735 and 736, and the power rail 737 are indicated as one group ofconductive rails for providing signals to one device unit (i.e., thedevice unit DU1 shown in FIG. 4 ). In some other embodiments, the powerrail 731 is coupled through vias (not shown) to transistors formed inthe fins 421 and 422, and the power rail 737 is coupled through vias(not shown) to transistors formed in the fins 423 and 424. Alternativelystated, the power rails 731 and 737 are coupled to a device unitincluding two transistors of different types formed in the adjacent finsFN, including the fins 421, 422, 423 and 424. In various embodiments,the signal rails 732, 733, 734, 735 and 736 are coupled through vias(not shown) to transistors formed in the fins 421, 422, 423 and 424.Alternatively stated, the signal rails 732, 733, 734, 735 and 736 arecoupled to a device unit that is further coupled to the power rails 731and 737.

Furthermore, the signal rail 738 is partially overlapped with the fin425 in a layout view. The signal rail 739 is substantially disposed overthe fin 426. The signal rail 740 is directly disposed over anintersected edge between two adjacent logic cells. The signal rail 741is directly overlapped with the fin 441 in a layout view. The signalrail 742 is directly overlapped with the fin 442 in a layout view.Moreover, the power rail 743 is not overlapped with the fins FN.Alternatively stated, the power rail 743 is separated from the fin 442of one group (i.e., the group T4 shown in FIG. 4 ) and the fin 443 ofanother adjacent group (i.e., the group T5 shown in FIG. 4 ).

In some embodiments, the power rail 737, the signal rails 738, 739, 740,741 and 742, and the power rail 743 are indicated as one group ofconductive rails for providing signals to one device unit (i.e., thedevice unit DU2 shown in FIG. 4 ). In some other embodiments, the powerrail 737 is coupled through vias (not shown) to transistors formed inthe fins 425 and 426, and the power rail 743 is coupled through vias(not shown) to transistors formed in the fins 441 and 442. Alternativelystated, the power rails 737 and 743 are coupled to a device unitincluding two transistors of different types formed in the adjacent finsFN, including the fins 425, 426, 441 and 442. In various embodiments,the signal rails 738, 739, 740, 741 and 742 are coupled through vias(not shown) to transistors formed in the fins 425, 426, 441 and 442.Alternatively stated, the signal rails 738, 739, 740, 741 and 742 arecoupled to a device unit that is further coupled to the power rails 737and 743.

Moreover, the signal rail 744 is partially overlapped with the fin 443in a layout view. The signal rail 745 is substantially disposed over thefin 444. The signal rail 746 is not overlapped with the fins FN.Alternatively stated, the signal rail 746 is separated from the fin 444of one group (i.e., the group T5 shown in FIG. 4 ) and the fin 445 ofanother adjacent group (i.e., the group T6 shown in FIG. 4 ). The signalrail 747 is directly overlapped with the fin 445 in a layout view. Thesignal rail 748 is directly overlapped with the fin 446 in a layoutview.

In some embodiments, the power rail 743, the signal rails 744, 745, 746,747 and 748, and the power rail 749 are indicated as one group ofconductive rails for providing signals to one device unit (i.e., thedevice unit DU3 shown in FIG. 4 ). In some other embodiments, the powerrail 743 is coupled through vias (not shown) to transistors formed inthe fins 443 and 444, and the power rail 749 is coupled through vias(not shown) to transistors formed in the fins 445 and 446. Alternativelystated, the power rails 743 and 749 are coupled to a device unitincluding two transistors of different types formed in the adjacent finsFN, including the fins 443, 444, 445 and 446. In various embodiments,the signal rails 738, 739, 740, 741 and 742 are coupled through vias(not shown) to transistors formed in the fins 443, 444, 445 and 446.Alternatively stated, the signal rails 744, 745, 746, 747 and 748 arecoupled to a device unit that is further coupled to the power rails 743and 749.

In some embodiments, the power rails PG is made of metal. In some otherembodiments, the power rails PG is coupled through vias (not shown) toat least one power circuit (not shown, e.g., a current source or avoltage source) disposed in a metal layer (e.g., metal-one (M1) layer)above the M0 layer, for receiving power signals. In various embodiments,the power rails PG are coupled through vias, disposed between the finsFN and the M0 layer, to the fins FN disposed below the M0 layer, forproviding the power signals to the corresponding transistors formed inthe fins FN. In some embodiments, at least one power rail PG isconfigured to provide signals with a first voltage, and at least onepower rail PG is configured to provide signals with a second voltage,wherein the first voltage is higher than the second voltage. This powerrail PG with the first voltage is indicated as a power line, and thispower rail with the second voltage is indicated as a ground line. Forexample, in some embodiments, with reference to FIG. 7A, the power rails713 and 717 in the bit cells and the power rails 731 and 743 in thelogic cells are referred to as the power lines. The power rails 711, 715and 719 in the bit cells and the power rails 737 and 749 in the logiccells are referred to as the ground lines. The power lines and theground lines are disposed intersected to each other.

In some embodiments, the signal rails SL is made of metal. In some otherembodiments, the signal rails SL are coupled through vias (not shown) toat least one data circuit (not shown) disposed in the M1 layer, forreceiving data signals. In various embodiments, the signal rails SL arecoupled through vias (not shown) to the fins FN, for providing the datasignals to the corresponding transistors formed in the fins FN.

In some embodiments, the signal rails SL in the bit cells are configuredto provide signals with bit data, and these signal rails SL areindicated as bit lines. For example, in some embodiments, with referenceto FIG. 7A, the signal rails 712, 714, 716 and 718 in the bit cells arereferred to as bit lines. Each of the signal rails 712, 714, 716 and 718are disposed between one of the power rails 713 and 717 as power metalrails and one of the power rails 711, 715 and 719 as ground rails. Insome embodiments, the signal rails 712 and 714 are a bit line pair thatis coupled to one row of the memory device (which is the memory deviceMC1 in FIG. 4 ). Similarly, the signal rails 716 and 718 are another bitline pair that is coupled to another row of the memory device (which isthe memory device MC1 in FIG. 4 ).

In some embodiments, the signal rails SL in the logic cells areconfigured to provide signals for operating logic functions, and thesesignal rails SL are indicated as signal lines. For example, in someembodiments, with reference to FIG. 7A, the signal rails 732, 733, 734,735 and 736 disposed between one of the power rails 731 as power metalrail and the same 737 as ground rail in the logic cells are referred toas signal lines. Similarly, the signal rails 738, 739, 740, 741 and 742in the logic cells are referred to as signal lines, and these signallines are disposed between one of power rails 737 as ground line and thesame 743 as power line. The signal rails 744, 745, 746, 747 and 748 inthe logic cells are referred to as signal lines, and these signal linesare disposed between one of power rails 743 as power line and the same749 as ground line.

With reference to FIG. 7B, it only illustrates elements disposed in theM0 layer shown in FIG. 7A for simplicity. A width of one of the powerrails PG in the bit cells is indicated as a width W1. A width of one ofthe signal rails SL in the bit cells is indicated as a width W2. A widthof another one of the power rails PG in the bit cells is indicated as awidth W3. A width of one of the power rails PG in the logic cells isindicated as a width W4. A width of one of the signal rails SL in thelogic cells is indicated as a width W5. For simplicity, only few powerrails PG or signal rails SL are labeled with widths W1-W5 illustrated inFIG. 7B.

In some embodiments, with reference to FIG. 7B, in the bit cells, thepower rails 711, 715 and 719 are indicated as the ground lines and eachof which has the width W1. In the bit cells, the power rails 713 and 717are indicated as the power lines and each of which has the width W2. Inthe bit cells, the signal rails 712, 714, 716 and 718 are indicated asthe bit lines and each of which has the width W3.

In some embodiments, with reference to FIG. 7B, in the logic cells, thepower rails 731 and 743 are indicated as the power lines and each ofwhich has the width W4. In logic cells, the power rails 737 and 749 areindicated as ground lines and each of which also has the width W4. Inlogic cells, the signal rails 732, 733, 734, 735, 736, 738, 739, 740,741, 742, 744, 745, 746, 747 and 748 are indicated as the signal linesand each of which has the width W5.

In some embodiments, the widths W1-W5 are different from one another. Insome other embodiments, the width W1 is substantially equal to the widthW2 or the width W4. In various embodiments, the width W1 is smaller thanor larger than the width W2, and the width W1 is smaller than or largerthan the width W4. In some embodiments, the width W4 is larger than thewidth W5.

In some embodiments, the width W4 is larger than a width of the fins FN.The width of the fins FN is also referred to as the fin width P shown inFIGS. 4 and 6A. In various embodiments, the width W5 is larger than thefin width P. In alternative embodiments, the width W5 is substantiallyequal to fin width P. In some embodiments, the width W4 is smaller thanor equal to a distance between two adjacent groups TN in the logic cells(e.g., between the group T1 and T2 shown in FIG. 4 ). In some otherembodiments, the width W4 is substantially equal to a distance betweentwo adjacent groups TN in the logic cells. In various embodiments, thewidth W5 is smaller than a distance between two adjacent groups TN inthe logic cells.

Reference now made to FIG. 8A. FIG. 8A is a flow chart of a method 800Afor generating an integrated circuit (IC) layout diagram of the memorydevice MC0 shown in FIG. 2 or the memory device MC1 shown in FIG. 3 , inaccordance with some embodiments of the present disclosure. In someembodiments, the layout diagram generated by the method 800A correspondsto the layout diagram ML1 shown in FIGS. 4, 6A-6B or 7A-7B. In someother embodiments, the layout diagram generated by the method 800Acorresponds to the layout diagram ML2 shown in FIG. 5 . For illustrationin FIG. 8A, the method 800A includes operations S810 a, S820 a, and S830a. Following illustrations of the method 800A in FIG. 8A with referenceto the layout diagram in FIG. 4 or 6A-6B include exemplary operations.However, the operations in FIG. 8A are not necessarily performed in theorder shown. Alternatively stated, operations may be added, replaced,changed order, and/or eliminated as appropriate, in accordance with thespirit and scope of various embodiments of the present disclosure.

In operation S810 a, fin regions, which are separated from each otherand extend along rows, are arranged in a logic cell. The logic cell isdisposed next to a memory cell, and both of the logic cell and thememory cell are included in a memory device. For illustration, as shownin FIG. 3 , the active regions AA1-AA3, which are separated from eachother and extend along rows, are arranged in the logic cells 320 and 340that are disposed next to the bit cells 310 and 330 included in thememory device MC1.

In some embodiments, the method 800A further includes the followingoperations. A distance between two adjacent fins is determined. Forillustration, as shown in FIG. 6A, a distance between two adjacent finsFN in the group T1 is determined to be the distance S3. In some otherembodiments, a distance between two adjacent fins is determined based onfin grids in a layout view, and each of the fin grids is separated fromone another by the fin pitch. For further illustration, as shown in FIG.6A, the distance S3 is determined based on the fin grids FN′, and eachof the fin grids FN′ is separated from one another by the fin pitch.

In operation S820 a, the fin regions are separated into fin groups.Alternatively stated, the fin regions are grouped or split into severalgroups that are arranged in rows. For illustration, as shown in FIG. 3 ,the active regions AA1-AA3 are separated into groups T1-T6, forgenerating respective transistors.

In operation S830 a, fins disposed in the fin regions are generated. Thefins of corresponding transistors are constructed in the fin regions.Therefore, the transistors are further generated based on thearrangement of the fin regions. For illustration, as shown in FIG. 3 ,the fins 321-326 and 341-346 are generated in the active regions AA1-AA3correspondingly.

In some embodiments, the method 800A further includes the followingoperations. In the logic cell, the conductive rails including powerrails and signal rails are arranged in a metal layer above the finregions. In the logic cell, the power rails are separated from the finsin a layout view. For illustration, as shown in FIG. 7A, in the logiccells, the conductive rails including power rails PG and signal rails SLare arranged in the M0 layer above the active regions. Also illustratedin FIG. 7A, in the logic cell, the power rails PG are separated from thefins FN in a layout view.

In some embodiments, the method 800A further includes the followingoperations. In the logic cell, at least one of the signal rails ispartially overlapped with the fins in a layout view. For illustration,as shown in FIG. 7A, in the logic cells, at least one of the signalrails SL, for example, including the signal rail 732, is partiallyoverlapped with the fins FN in a layout view.

FIG. 8B is a flow chart of a method 800B for fabricating an integratedcircuit (IC) including the memory device MC0 shown in FIG. 2 or thememory device MC1 shown in FIG. 3 , in accordance with some embodimentsof the present disclosure. For illustration in FIG. 8B, the method 800Bincludes operations S810 b, S820 b, S830 b and S840 b. Followingillustrations of the method 800B in FIG. 8B with reference to the memorydevice and the layout diagrams thereof in FIGS. 4, 6A-6B or 7A-7Binclude exemplary operations. However, the operations in FIG. 8B are notnecessarily performed in the order shown. Alternatively stated,operations may be added, replaced, changed order, and/or eliminated asappropriate, in accordance with the spirit and scope of variousembodiments of the present disclosure.

In operation S810 b, fin regions are formed in a logic cell that isdisposed next to a bit cell. The fin regions are separated from eachother and extend along a row direction. In some embodiments, the finregions correspond to the active regions AA1-AA3 shown in FIG. 3 . Insome embodiments, the logic cell corresponds to the logic cell 320 or340 shown in FIG. 3 , and the bit cell corresponds to the bit cell 310or 330 shown in FIG. 3 .

In operation S820 b, the fin regions are separated into fin groups. Insome embodiments, fin groups correspond to the groups T1-T6 shown inFIG. 3 . In some embodiments, a distance between at least two adjacentfin groups is different from a distance between another two adjacent fingroups.

In operation S830 b, fins are formed in the fin regions. In someembodiments, the fins correspond to the fins 321-326 or 341-346 shown inFIG. 3 . In some embodiments, a distance between the fins is greaterthan or equal to the fin pitch.

In operation S840 b, transistors are generated. The transistors includethe fins that are formed in the operation S830 b. In some embodiments,the transistors correspond to the transistors T1-T6 shown in FIG. 3 .

Reference is now made to FIG. 9 . FIG. 9 is a block diagram ofelectronic design automation (EDA) system 900 for designing theintegrated circuit layout design, in accordance with some embodiments ofthe present disclosure. EDA system 900 is configured to implement one ormore operations of the method 800 disclosed in FIG. 8A or the method800B disclosed in FIG. 8B, and further explained in conjunction withFIGS. 3-4, 6A-6B and 7A-7B. In some embodiments, EDA system 900 includesan APR system.

In some embodiments, EDA system 900 is a general purpose computingdevice including a hardware processor 920 and a non-transitory,computer-readable storage medium 960. Storage medium 960, amongst otherthings, is encoded with, i.e., stores, computer program code(instructions) 961, i.e., a set of executable instructions. Execution ofinstructions 961 by hardware processor 920 represents (at least in part)an EDA tool which implements a portion or all of, e.g., the method 800Aor 800B.

The processor 920 is electrically coupled to computer-readable storagemedium 960 via a bus 950. The processor 920 is also electrically coupledto an I/O interface 910 and a fabrication tool 970 by bus 950. A networkinterface 930 is also electrically connected to processor 920 via bus950. Network interface 930 is connected to a network 940, so thatprocessor 920 and computer-readable storage medium 960 are capable ofconnecting to external elements via network 940. The processor 920 isconfigured to execute computer program code 961 encoded incomputer-readable storage medium 960 in order to cause EDA system 900 tobe usable for performing a portion or all of the noted processes and/ormethods. In one or more embodiments, processor 920 is a centralprocessing unit (CPU), a multi-processor, a distributed processingsystem, an application specific integrated circuit (ASIC), and/or asuitable processing unit.

In one or more embodiments, computer-readable storage medium 960 is anelectronic, magnetic, optical, electromagnetic, infrared, and/or asemiconductor system (or apparatus or device). For example,computer-readable storage medium 960 includes a semiconductor orsolid-state memory, a magnetic tape, a removable computer diskette, arandom access memory (RAM), a read-only memory (ROM), a rigid magneticdisk, and/or an optical disk. In one or more embodiments using opticaldisks, computer-readable storage medium 960 includes a compact disk-readonly memory (CD-ROM), a compact disk-read/write (CD-R/W), and/or adigital video disc (DVD).

In one or more embodiments, storage medium 960 stores computer programcode 961 configured to cause EDA system 900 (where such executionrepresents (at least in part) the EDA tool) to be usable for performinga portion or all of the noted processes and/or methods. In one or moreembodiments, storage medium 960 also stores information whichfacilitates performing a portion or all of the noted processes and/ormethods. In one or more embodiments, storage medium 960 stores library962 of standard cells including such standard cells as disclosed herein,for example, a memory cell included in the array of cells 410-440discussed above with respect to FIG. 4 .

EDA system 900 includes I/O interface 910. I/O interface 910 is coupledto external circuitry. In one or more embodiments, I/O interface 910includes a keyboard, keypad, mouse, trackball, trackpad, touchscreen,and/or cursor direction keys for communicating information and commandsto processor 920.

EDA system 900 also includes network interface 930 coupled to processor920. Network interface 930 allows EDA system 900 to communicate withnetwork 940, to which one or more other computer systems are connected.Network interface 930 includes wireless network interfaces such asBLUETOOTH, WIFI, WIMAX, GPRS, or WCDMA; or wired network interfaces suchas ETHERNET, USB, or IEEE-1364. In one or more embodiments, a portion orall of noted processes and/or methods, is implemented in two or more EDAsystems 900.

EDA system 900 also includes the fabrication tool 970 coupled to theprocessor 920. The fabrication tool 970 is configured to fabricateintegrated circuits, including, for example, the memory device MC0 orMC1 implemented by a semiconductor device 100 illustrated in FIG. 1 ,based on the design files processed by the processor 920 and/or the IClayout designs as discussed above.

EDA system 900 is configured to receive information through I/Ointerface 910. The information received through I/O interface 910includes one or more of instructions, data, design rules, libraries ofstandard cells, and/or other parameters for processing by processor 920.The information is transferred to processor 920 via bus 950. EDA system900 is configured to receive information related to a UI through I/Ointerface 910. The information is stored in computer-readable medium 960as user interface (UI) 963.

In some embodiments, a portion or all of the noted processes and/ormethods is implemented as a standalone software application forexecution by a processor. In some embodiments, a portion or all of thenoted processes and/or methods is implemented as a software applicationthat is a part of an additional software application. In someembodiments, a portion or all of the noted processes and/or methods isimplemented as a plug-in to a software application. In some embodiments,at least one of the noted processes and/or methods is implemented as asoftware application that is a portion of an EDA tool. In someembodiments, a portion or all of the noted processes and/or methods isimplemented as a software application that is used by EDA system 900. Insome embodiments, a layout diagram which includes standard cells isgenerated using a tool such as VIRTUOSO® available from CADENCE DESIGNSYSTEMS, Inc., or another suitable layout generating tool.

In some embodiments, the processes are realized as functions of aprogram stored in a non-transitory computer readable recording medium.Examples of a non-transitory computer readable recording medium include,but are not limited to, external/removable and/or internal/built-instorage or memory unit, for example, one or more of an optical disk,such as a DVD, a magnetic disk, such as a hard disk, a semiconductormemory, such as a ROM, a RAM, a memory card, and the like.

FIG. 10 is a block diagram of IC manufacturing system 1000, and an ICmanufacturing flow associated therewith, in accordance with someembodiments of the present disclosure. In some embodiments, based on alayout diagram, at least one of (A) one or more semiconductor masks or(B) at least one component in a layer of a semiconductor integratedcircuit is fabricated using IC manufacturing system 1000.

In FIG. 10 , IC manufacturing system 1000 includes entities, such as adesign house 1010, a mask house 1020, and an IC manufacturer/fabricator(“fab”) 1030, that interact with one another in the design, development,and manufacturing cycles and/or services related to manufacturing an ICdevice 1040. The entities in IC manufacturing system 1000 are connectedby a communications network. In some embodiments, the communicationsnetwork is a single network. In some embodiments, the communicationsnetwork is a variety of different networks, such as an intranet and theInternet. The communications network includes wired and/or wirelesscommunication channels. Each entity interacts with one or more of theother entities and provides services to and/or receives services fromone or more of the other entities. In some embodiments, two or more ofdesign house 1010, mask house 1020, and IC fab 1030 is owned by a singlelarger company. In some embodiments, two or more of design house 1010,mask house 1020, and IC fab 1030 coexist in a common facility and usecommon resources.

Design house (or design team) 1010 generates an IC design layout diagram1011. IC design layout diagram 1011 includes various geometricalpatterns, for example, an IC layout design depicted in FIG. 4, 5, 6A-6Band/or FIG. 7A-7B, designed for an IC device 1040, for example, memorydevice MC1, discussed above with respect to FIG. 3 . The geometricalpatterns correspond to patterns of metal, oxide, or semiconductor layersthat make up the various components of IC device 1040 to be fabricated.The various layers combine to form various IC features. For example, aportion of IC design layout diagram 1011 includes various IC features,such as an fin, gate electrode, source and drain, conductive segments orvias of an interlayer interconnection, to be formed in a semiconductorsubstrate (such as a silicon wafer) and various material layers disposedon the semiconductor substrate. Design house 1010 implements a properdesign procedure to form IC design layout diagram 1011. The designprocedure includes one or more of logic design, physical design or placeand route. IC design layout diagram 1011 is presented in one or moredata files having information of the geometrical patterns. For example,IC design layout diagram 1011 can be expressed in a GDSII file format orDFII file format.

Mask house 1020 includes mask data preparation 1021 and mask fabrication1022. Mask house 1020 uses IC design layout diagram 1011 to manufactureone or more masks 1023 to be used for fabricating the various layers ofIC device 1040 according to IC design layout diagram 1011. Mask house1020 performs mask data preparation 1021, where IC design layout diagram1011 is translated into a representative data file (“RDF”). Mask datapreparation 1021 provides the RDF to mask fabrication 1022. Maskfabrication 1022 includes a mask writer. A mask writer converts the RDFto an image on a substrate, such as a mask (reticle) 1023 or asemiconductor wafer 1033. The IC design layout diagram 1011 ismanipulated by mask data preparation 1021 to comply with particularcharacteristics of the mask writer and/or requirements of IC fab 1030.In FIG. 10 , data preparation 1021 and mask fabrication 1022 areillustrated as separate elements. In some embodiments, data preparation1021 and mask fabrication 1022 can be collectively referred to as maskdata preparation.

In some embodiments, mask data preparation 1021 includes opticalproximity correction (OPC) which uses lithography enhancement techniquesto compensate for image errors, such as those that can arise fromdiffraction, interference, other process effects and the like. OPCadjusts IC design layout diagram 1011. In some embodiments, datapreparation 1021 includes further resolution enhancement techniques(RET), such as off-axis illumination, sub-resolution assist features,phase-shifting masks, other suitable techniques, and the like orcombinations thereof. In some embodiments, inverse lithographytechnology (ILT) is also used, which treats OPC as an inverse imagingproblem.

In some embodiments, data preparation 1021 includes a mask rule checker(MRC) that checks the IC design layout diagram 1011 that has undergoneprocesses in OPC with a set of mask creation rules which contain certaingeometric and/or connectivity restrictions to ensure sufficient margins,to account for variability in semiconductor manufacturing processes, andthe like. In some embodiments, the MRC modifies the IC design layoutdiagram 1011 to compensate for limitations during mask fabrication 1022,which may undo part of the modifications performed by OPC in order tomeet mask creation rules.

In some embodiments, data preparation 1021 includes lithography processchecking (LPC) that simulates processing that will be implemented by ICfab 1030 to fabricate IC device 1040. LPC simulates this processingbased on IC design layout diagram 1011 to create a simulatedmanufactured device, such as IC device 1040. The processing parametersin LPC simulation can include parameters associated with variousprocesses of the IC manufacturing cycle, parameters associated withtools used for manufacturing the IC, and/or other aspects of themanufacturing process. LPC takes into account various factors, such asaerial image contrast, depth of focus (“DOF”), mask error enhancementfactor (“MEEF”), other suitable factors, and the like or combinationsthereof. In some embodiments, after a simulated manufactured device hasbeen created by LPC, if the simulated device is not close enough inshape to satisfy design rules, OPC and/or MRC are be repeated to furtherrefine IC design layout diagram 1011.

It should be understood that the above description of data preparation1021 has been simplified for the purposes of clarity. In someembodiments, data preparation 1021 includes additional features such asa logic operation (LOP) to modify the IC design layout diagram 1011according to manufacturing rules. Additionally, the processes applied toIC design layout diagram 1011 during data preparation 1021 may beexecuted in a variety of different orders.

After data preparation 1021 and during mask fabrication 1022, a mask1023 or a group of masks 1023 are fabricated based on the modified ICdesign layout diagram 1011. In some embodiments, mask fabrication 1022includes performing one or more lithographic exposures based on ICdesign layout diagram 1011. In some embodiments, an electron-beam(e-beam) or a mechanism of multiple e-beams is used to form a pattern ona mask (photomask or reticle) 1023 based on the modified IC designlayout diagram 1011. Mask 1023 can be formed in various technologies. Insome embodiments, mask 1023 is formed using binary technology. In someembodiments, a mask pattern includes opaque regions and transparentregions. A radiation beam, such as an ultraviolet (UV) beam, used toexpose the image sensitive material layer (for example, photoresist)which has been coated on a wafer, is blocked by the opaque region andtransmits through the transparent regions. In one example, a binary maskversion of mask 1023 includes a transparent substrate (for example,fused quartz) and an opaque material (for example, chromium) coated inthe opaque regions of the binary mask. In another example, mask 1023 isformed using a phase shift technology. In a phase shift mask (PSM)version of mask 1023, various features in the pattern formed on thephase shift mask are configured to have proper phase difference toenhance the resolution and imaging quality. In various examples, thephase shift mask can be attenuated PSM or alternating PSM. The mask(s)generated by mask fabrication 1022 is used in a variety of processes.For example, such a mask(s) is used in an ion implantation process toform various doped regions in semiconductor wafer 1033, in an etchingprocess to form various etching regions in semiconductor wafer 1033,and/or in other suitable processes.

IC fab 1030 includes wafer fabrication 1032. IC fab 1030 is an ICfabrication business that includes one or more manufacturing facilitiesfor the fabrication of a variety of different IC products. In someembodiments, IC fab 1030 is a semiconductor foundry. For example, theremay be a manufacturing facility for the front end fabrication of aplurality of IC products (front-end-of-line (FEOL) fabrication), while asecond manufacturing facility may provide the back end fabrication forthe interconnection and packaging of the IC products (back-end-of-line(BEOL) fabrication), and a third manufacturing facility may provideother services for the foundry business.

IC fab 1030 uses mask(s) 1023 fabricated by mask house 1020 to fabricateIC device 1040. Thus, IC fab 1030 at least indirectly uses IC designlayout diagram 1011 to fabricate IC device 1040. In some embodiments,semiconductor wafer 1033 is fabricated by IC fab 1030 using mask(s) 1023to form IC device 1040. In some embodiments, the IC fabrication includesperforming one or more lithographic exposures based at least indirectlyon IC design layout diagram 1011. Semiconductor wafer 1033 includes asilicon substrate or other proper substrate having material layersformed thereon. Semiconductor wafer 1033 further includes one or more ofvarious doped regions, dielectric features, multilevel interconnects,and the like (formed at subsequent manufacturing steps).

Also disclosed is a method including: abutting a first logic cell havinga first cell height to a first memory cell having the first cell height;forming a first conductive rail and a second conductive rail at oppositesides of the first memory cell, respectively; forming a plurality offirst conductive rails between the first conductive rail and the secondconductive rail; forming a third conductive rail and a fourth conductiverail at opposite sides of the first logic cell, respectively; andforming a plurality of second conductive rails between the thirdconductive rail and the fourth conductive rail. An amount of theplurality of second conductive rails is larger than an amount of theplurality of first conductive rails.

Also disclosed is a method including: abutting a first logic cell to afirst memory cell and a second logic cell having a first height;abutting a second memory cell having the first height to the firstmemory cell and the second logic cell; forming a first fin group in thefirst logic cell; forming a second fin group, a third fin group and afourth fin group in the second logic cell; and forming a firsttransistor, a second transistor, a third transistor and a fourthtransistor by the first fin group, the second fin group, the third fingroup and the fourth fin group, respectively. The first transistor andthe second transistor are adjacent with each other, and the thirdtransistor and the fourth transistor are adjacent with each other.

Also disclosed is a method including: aligning a first logic cell with afirst memory cell; and aligning each of a first fin of the first logiccell and a second fin of the first memory cell to with a plurality offin grids. A third fin of the first memory cell is not aligned with theplurality of fin grids.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method, comprising: abutting a first logic cellhaving a first cell height to a first memory cell having the first cellheight; forming a first conductive rail and a second conductive rail atopposite sides of the first memory cell, respectively; forming aplurality of first conductive rails between the first conductive railand the second conductive rail; forming a third conductive rail and afourth conductive rail at opposite sides of the first logic cell,respectively; and forming a plurality of second conductive rails betweenthe third conductive rail and the fourth conductive rail, wherein anamount of the plurality of second conductive rails is larger than anamount of the plurality of first conductive rails.
 2. The method ofclaim 1, further comprising: abutting a second logic cell having asecond cell height to a second memory cell having the second cellheight; abutting the second logic cell and the second memory cell to thefirst logic cell and the first memory cell, respectively; forming afifth conductive rail and the second conductive rail at opposite sidesof the second memory cell, respectively; forming a plurality of thirdconductive rails between the fifth conductive rail and the secondconductive rail; forming a sixth conductive rail and the fourthconductive rail at opposite sides of the second logic cell,respectively; and forming a plurality of fourth conductive rails betweenthe sixth conductive rail and the fourth conductive rail, wherein anamount of the plurality of fourth conductive rails is larger than anamount of the plurality of third conductive rails.
 3. The method ofclaim 1, further comprising: forming a first fin and a second fin in thefirst memory cell; forming a third fin and a fourth fin in the firstlogic cell; aligning the first fin and the second fin to the third finand the fourth fin, respectively; coupling a fifth conductive rail ofthe plurality of first conductive rails to each of the first fin and thesecond fin; disposing a sixth conductive rail of the plurality of secondconductive rails over the third fin; and disposing a seventh conductiverail of the plurality of second conductive rails over the fourth fin,wherein the sixth conductive rail is adjacent to the seventh conductiverail, and the third fin is adjacent to the fourth fin.
 4. The method ofclaim 3, further comprising: forming a fifth fin in the first memorycell; and forming a sixth fin and a seventh fin in the first logic cell,wherein the sixth fin and the seventh fin are adjacent with each otherand extend along a first direction, and the fifth fin is disposedbetween the sixth fin and the seventh fin along a second directiondifferent from the first direction.
 5. The method of claim 4, furthercomprising: disposing an eighth conductive rail of the plurality offirst conductive rails over the fifth fin; disposing a ninth conductiverail of the plurality of second conductive rails over the sixth fin; anddisposing a tenth conductive rail of the plurality of second conductiverails over the sixth fin, wherein the ninth conductive rail and thetenth conductive rail are adjacent with each other, and the eighthconductive rail is between the fifth conductive rail and the firstconductive rail.
 6. The method of claim 5, further comprising: disposinga eleventh conductive rail of the plurality of second conductive railsbetween the tenth conductive rail and the sixth conductive rail; andseparating the eleventh conductive rail from each of the seventh fin andthe third fin.
 7. The method of claim 1, further comprising: forming afirst fin and a second fin in the first logic cell; and forming a thirdfin in the first memory cell, wherein the first fin and the second finare adjacent with each other and extend along a first direction, and thethird fin is disposed between the first fin and the second fin along asecond direction different from the first direction.
 8. The method ofclaim 7, further comprising: disposing a fifth conductive rail of theplurality of first conductive rails over the third fin; disposing asixth conductive rail of the plurality of second conductive rails overthe second fin; and disposing a seventh conductive rail of the pluralityof second conductive rails over the third fin, wherein the sixthconductive rail and the seventh conductive rail are adjacent with eachother.
 9. A method, comprising: abutting a first logic cell to a firstmemory cell and a second logic cell having a first height; abutting asecond memory cell having the first height to the first memory cell andthe second logic cell; forming a first fin group in the first logiccell; forming a second fin group, a third fin group and a fourth fingroup in the second logic cell; and forming a first transistor, a secondtransistor, a third transistor and a fourth transistor by the first fingroup, the second fin group, the third fin group and the fourth fingroup, respectively, wherein the first transistor and the secondtransistor are adjacent with each other, and the third transistor andthe fourth transistor are adjacent with each other.
 10. The method ofclaim 9, further comprising: forming a fifth fin group in the firstlogic cell; forming a sixth fin group in the first logic cell; andforming a fifth transistor and a sixth transistor by the fifth fin groupand the sixth fin group, respectively, wherein the fifth transistor andthe sixth transistor are adjacent with each other.
 11. The method ofclaim 9, further comprising: separating the third fin group from thefourth fin group by a first distance; and separating the third fin groupfrom the second fin group by a second distance different from the firstdistance.
 12. The method of claim 9, further comprising: separating afirst fin of the third fin group from a second fin of the third fingroup by a first distance; and separating a third fin of the fourth fingroup from a fourth fin of the fourth fin group by a second distancedifferent from the first distance, wherein the first fin and the secondfin are adjacent with each other, and the third fin and the fourth finare adjacent with each other.
 13. The method of claim 12, furthercomprising: aligning a fifth fin in the second memory cell to the secondfin; and disposing a sixth fin in the second memory cell between thethird fin and the fourth fin along a first direction, wherein the firstlogic cell and the second logic cell are arranged along the firstdirection.
 14. The method of claim 9, further comprising: disposing thethird fin group on a plurality of fin grids; and arranging each of thesecond fin group and the fourth fin group off the plurality of fingrids.
 15. A method, comprising: aligning a first logic cell with afirst memory cell; and aligning each of a first fin of the first logiccell and a second fin of the first memory cell to with a plurality offin grids, wherein a third fin of the first memory cell is not alignedwith the plurality of fin grids.
 16. The method of claim 15, furthercomprising: arranging a first fin group of the first logic cell off theplurality of fin grids; and disposing the third fin between a fourth finof the first fin group and a fifth fin of the first fin group along afirst direction, wherein first fin group extends along a seconddirection different from the first direction, and the first fin group isadjacent to the first fin.
 17. The method of claim 16, furthercomprising: disposing the fourth fin between the third fin and a sixthfin of the first memory cell along a first direction, wherein the sixthfin and the third fin are adjacent with each other.
 18. The method ofclaim 17, further comprising: aligning each of a seventh fin of thefirst logic cell to with the plurality of fin grids, wherein a distancebetween the seventh fin and the first fin is approximately equal to adistance between the fourth fin and the fifth fin.
 19. The method ofclaim 18, further comprising: arranging a second fin group of the firstlogic cell off the plurality of fin grids; and disposing an eighth finof the first memory cell between a ninth fin of the second fin group anda tenth fin of the second fin group along the first direction, whereinsecond fin group extends along the second direction, and the second fingroup is adjacent to the seventh fin.
 20. The method of claim 19,further comprising: disposing the tenth fin between the eighth fin andan eleventh fin of the first memory cell along a first direction,wherein the eleventh fin and the eighth fin are adjacent with eachother.